PREDICTION OF WATER IN ASTEROIDS FROM SPECTRAL DATA SHORTWARD OF 3 MU-M

Spectra of many asteroids display a 3 mu m absorption feature that has been associated with the presence of water of hydration in clays or h ydrated salts. Detection of this feature, however, is difficult throug h the Earth's atmosphere for various reasons. Correlations were sought and detected between the 3 mu m absorption band and features shortwar d of 3 mu m, which enabled us to construct a tool for the prediction o f water in asteroids from the shorter wavelength part of the spectrum. Such a prediction tool can help concentrate observing resources to th ose objects most likely to have water. Artificial neural network techn iques were used for the investigation of the above correlations and fo r the prediction of the hydration state of objects, We can predict the presence of water from the <3 mu m spectral window with a high, appro ximately 90% success rate for spectra for which prediction is possible . However, for about half the spectra in this study, no decision could be made, for lack of sufficient training information. We expect this situation to improve steadily as new data become available. (C) 1997 A cademic Press.